Devices and methods for placement of loss control slurry

ABSTRACT

An LCM placement device for placement of an LCM onto a test bed in a test cell is provided. The LCM placement device minimizes or prevents damage and degradation of the test bed during placement of the LCM. The device includes a funnel-shaped feeder, a cylindrical shaft, an inverted funnel-shaped dispenser, and an energy-absorbing disc coupled to the inverted funnel-shaped dispenser by legs. Processes for placement of an LCM onto a test bed in a test cell are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority from U.S.Non-provisional application Ser. No. 16/594,593 filed Oct. 7, 2019, andtitled “DEVICES AND METHODS FOR PLACEMENT OF LOSS CONTROL SLURRY,” acopy of which is incorporated by reference in its entirety for purposesof United States patent practice.

BACKGROUND Field of the Disclosure

The present disclosure generally relates to the testing and evaluationof lost circulation materials (LCMs) used to control lost circulation ina wellbore during drilling with a drilling fluid. More specifically,embodiments of the disclosure relate to the placement of LCM slurries ona test bed.

Description of the Related Art

Lost circulation is one of the frequent challenges encountered duringdrilling operations. Lost circulation can be encountered during anystage of operations and occurs when drilling fluid (or drilling mud)pumped into a well returns partially or does not return to the surface.While some fluid loss is expected, excessive fluid loss is not desirablefrom a safety, an economical, or an environmental point of view. Lostcirculation is associated with problems with well control, boreholeinstability, pipe sticking, unsuccessful production tests, poorhydrocarbon production after well completion, and formation damage dueto plugging of pores and pore throats by mud particles. Lost circulationproblems may also contribute to non-productive time (NPT) for a drillingoperation. In extreme cases, lost circulation problems may forceabandonment of a well.

SUMMARY

Lost circulation materials (LCMs) are used to mitigate lost circulationby blocking the path of the drilling fluid (such as drilling mud) intothe formation. The type of LCM used in a lost circulation situationdepends on the extent of lost circulation and the type of formation.Different types of LCMs such as granular, fibrous, and flaky materialsare frequently used either alone or in combination to control loss ofcirculation.

Various types of test beds may be used to simulate different types ofloss zones and evaluate different LCMs for suitability and selection fora particular type of loss zone. For example, a 20/40 sand bed may beused to simulate a highly permeable loss zone that is prone to causepartial loss of circulation. In another example, a bed of carbonatechips having sizes in the range of 4 millimeters (mm) to 8 mm may beused to simulate an extremely permeable loss zones that causes moderateto severe loss of circulation. In another example, a bed of pebbleshaving sizes in the range of 20 mm to 30 mm may be used to simulate arubble or “super-K” loss zone that causes severe loss of circulation. Asused herein, the term “super-K” refers to zones that produce greaterthan 500 barrels per day per foot of thickness (BLPD/ft). The quality ofthe test bed is an important factor for reliable evaluation of LCMperformance. Ideally, there should be no or negligible degradation ofthe test bed during the placement of an LCM on top of the test bed. Thequality of test bed is directly related to the quality of the LCMtesting, the quality of the experimental data, and the reduction of themargin for errors of the experimental data.

An existing technique for the placement of an LCM (for example, an LCMpill or slurry) on a test bed is to introduce the LCM close to the testbed cell wall using a flexible tube. However, this technique may causesignificant damage or degradation to the top of the test bed dependingon the skills of the technician and is unable to ensure a quality testbed for superior data generation due to the damage and degradation. FIG.1 is a photograph 100 that depicts the damage caused at the top of atest bed while using this flexible tube technique with water as arepresentative of a LCM slurry. The damaged zone is shown in area 102and illustrates the damage caused by this technique.

Another proposed technique for placement of an LCM on top of a test bedis pouring an LCM slurry at the wall of a test cell by tilting the testcell at an angle of 10 degrees to 15 degrees so that a significantamount of kinetic energy is lost during the movement of the LCM slurryfrom the top of the test cell to the top of the test bed. However, thistechnique is difficult to implement, generates uncontrolled tilting ofthe test cell, and causes movement of the test bed material due to thetilting of the test cell. This technique also causes damage at theperiphery of the test bed. FIG. 2 is a photograph 200 that depicts thedamage caused at the periphery of a test bed while using this techniquewith an LCM slurry. The damaged zone is shown in area 202 andillustrates the damage caused by the tilting of the test cell andplacement of the LCM slurry.

Embodiments of the disclosure are directed to devices and processes forplacement of an LCM slurry on the top of a test bed to minimize orprevent damage and degradation of the test bed. As described in thedisclosure, placement of an LCM slurry using the devices and processesmaintain the quality of the test bed and improve the quality of the LCMtesting and experimental data as compared to prior art techniques.

In one embodiment, an apparatus for placement of a lost circulationmaterial (LCM) on a test bed in a test cell, the apparatus is provided.The apparatus includes a funnel-shaped portion that includes a mouthhaving a first diameter and an outlet having a second diameter, thefirst diameter greater than the second diameter, and a cylindrical shafthaving a first end and a second end, the funnel-shaped portionpositioned at a first end of the cylindrical shaft. The apparatus alsoincludes an inverted funnel-shaped portion positioned at a second end ofthe cylindrical shaft, the inverted funnel-shaped portion including aninlet having a third diameter and a mouth having a fourth diameter, anda disc coupled to the inverted-funnel shaped portion via a plurality oflegs, such that a surface of the disc is facing the mouth of theinverted funnel-shaped portion to define a distance between the surfaceof the disc and the mouth of the inverted funnel-shaped portion. Theapparatus is configured to convert axial flow through the cylindricalshaft to radial flow across the surface of the disc.

In some embodiments, the disc is formed from stainless steel. In someembodiments, the plurality of legs includes three legs around thecircumference of the cylindrical shaft such that each leg is located 120degrees from an adjacent leg. In some embodiments, the test bed is asand bed. In some embodiments, the disc has a disc diameter, such thatthe disc diameter is selected to provide for insertion of the disc intothe test cell containing the test bed. In some embodiments, thefunnel-shaped portion has a length of 70 millimeters (mm) and the firstdiameter of the mouth is 68 mm. In some embodiments, the cylindricalshaft has a length of 100 millimeters and an inner diameter of 10 mm. Insome embodiments, the inverted funnel-shaped portion has a length of 10millimeters (mm) and the fourth diameter of the mouth is 15 mm. In someembodiments, the disc has a length of 5 millimeters and a diameter of 68mm.

In another embodiment, a method for placing a lost circulation material(LCM) on a test bed in a test cell is provided. The method includespreparing a mixture having the LCM and inserting an LCM placementapparatus into the test cell. The LCM placement apparatus includes afunnel-shaped portion that includes a mouth having a first diameter andan outlet having a second diameter, the first diameter greater than thesecond diameter, and a cylindrical shaft having a first end and a secondend, the funnel-shaped portion positioned at a first end of thecylindrical shaft. The LCM placement apparatus also includes an invertedfunnel-shaped portion positioned at a second end of the cylindricalshaft, the inverted funnel-shaped portion including an inlet having athird diameter and a mouth having a fourth diameter, and a disc coupledto the inverted-funnel shaped portion via a plurality of legs, such thata surface of the disc is facing the mouth of the inverted funnel-shapedportion to define a distance between the surface of the disc and themouth of the inverted funnel-shaped portion. The method further includespouring the mixture onto an inner wall of the funnel-shaped portion ofthe LCM placement apparatus, such that the slurry flows axially throughthe cylindrical shaft and flows radially across a surface of the discafter exiting the inverted funnel-shaped portion.

In some embodiments, the mixture is a slurry. In some embodiments, thedisc is formed from stainless steel. In some embodiments, the pluralityof legs includes three legs around the circumference of the cylindricalshaft such that each leg is located 120 degrees from an adjacent leg. Insome embodiments, the test bed is a sand bed. In some embodiments, thedisc has a disc diameter, such that the disc diameter is selected toprovide for insertion of the disc into the test cell containing the testbed. In some embodiments, inserting an LCM placement apparatus into thetest cell includes an LCM placement apparatus into the test cell todefine a space between the test bed and a surface of the disc.

In another embodiment, a method of manufacturing an apparatus forplacement of a lost circulation material (LCM) on a test bed in a testcell is provided. The method includes connecting a funnel-shaped portionto a first end of a cylindrical shaft, the funnel-shaped portionincluding a mouth having a first diameter and an outlet having a seconddiameter, the first diameter greater than the second diameter andconnecting an inverted funnel-shaped portion to a second end of thecylindrical shaft, the inverted funnel-shaped dispenser including aninlet having a third diameter and a mouth having a fourth diameter. Themethod also includes coupling a disc to the inverted-funnel shapedportion via a plurality of legs, such that a surface of the disc facesthe mouth of the inverted funnel-shaped dispenser to define a distancebetween the surface of the disc and the mouth of the invertedfunnel-shaped dispenser. The apparatus is configured to convert axialflow through the cylindrical shaft to radial flow across the surface ofthe disc.

In some embodiments, coupling a disc to the inverted-funnel shapedportion via a plurality of legs includes welding the legs to theinverted-funnel shaped portion. In some embodiments, the disc is formedfrom stainless steel. In some embodiments, the plurality of legsincludes three legs around the circumference of the cylindrical shaftsuch that each leg is located 120 degrees from an adjacent leg.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph that depicts the damage caused at the top of atest bed while using a prior art technique with water as arepresentative of a LCM slurry;

FIG. 2 is a photograph that depicts the damage caused at the top of atest bed while using a prior art technique;

FIG. 3 is a photograph of an LCM placement device in accordance with anembodiment of the disclosure;

FIG. 4 is a schematic side view of an LCM placement device in accordancewith an embodiment of the disclosure;

FIG. 5 is a schematic side view of an LCM placement device inserted intoa test cell in accordance with an embodiment of the disclosure;

FIG. 6 is a block diagram of a process for using an LCM to place an LCMslurry on a test bed in a test cell in accordance with an embodiment ofthe disclosure; and

FIG. 7 is a photograph of a sand bed after placement of an LCM slurryusing an LCM placement device and process described in the disclosure.

DETAILED DESCRIPTION

The present disclosure will be described more fully with reference tothe accompanying drawings, which illustrate embodiments of thedisclosure. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to the illustratedembodiments. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art.

Embodiments of the disclosure are directed to an LCM placement deviceand process for placement of an LCM (for example, in an LCM slurry) onthe top of a test bed in a test cell. The device and process minimize orprevent damage and degradation of the test bed during placement of theLCM. The device includes a funnel-shaped feeder, a cylindrical shaft, aninverted funnel-shaped dispenser, and an energy-absorbing disc coupledto the inverted funnel-shaped dispenser by legs.

As described in the disclosure, the LCM placement device for placementof an LCM may reduce the kinetic and potential energies of an LCM slurrybefore it reaches the top of the test bed to minimize or prevent damageand degradation to the test bed. As described infra, the LCM placementdevice may convert axial flow to radial flow via an energy-absorbingdisc to further dissipate the kinetic and potential energies. Theenergy-absorbing disc also acts to divert the flow of the LCM slurry.

Although the LCM placement device and process may be described withreference to an LCM slurry, it should be appreciated that other mixturesmay be used in with the LCM placement device and process described inthe disclosure. For example, the LCM placement device and process may beused with an LCM fluid pill, an LCM with or without a carrier fluid, LCMsuspensions, and LCM fluids.

As will be appreciated, translational kinetic energy (that is, kineticenergy from translational motion) depends on the mass and velocity ofthe moving object. The kinetic energy is directly proportional to thesquare of the velocity. The device and process described in thedisclosure may significantly reduce the kinetic energy of an LCM slurrymoving through the device to avoid any damage and degradation of a testbed.

As will also be appreciated, the potential energy of the object is theenergy of an object's position relative to the position of anotherobjects. For an object falling from a higher position, there is a directrelationship between the potential energy and the dropping height; thepotential energy increases with an increase in dropping height ordecreases with a decrease in dropping height. The device and processdescribed in the disclosure reduces the potential energy of the LCMslurry by reducing the dropping height between the LCM and the top of atest bed (for example, some embodiments may reduce the dropping heightfrom about 100 mm to about 5 mm).

FIG. 3 is a photograph 300 of an LCM placement device 302 and FIG. 4 isa schematic side view of the LCM placement 302 in accordance with anembodiment of the disclosure. As shown in FIGS. 3 and 4, the device 302includes a funnel-shaped feeder 304 having a mouth 306, a cylindricalshaft 308, an inverted funnel-shaped dispenser 310, and anenergy-absorbing disc 312. The energy-absorbing disc 312 may be coupledto the inverted funnel-shaped dispenser 310 via legs 314. Theenergy-absorbing disc 312 is oriented such that a surface 316 (that is,a “face”) of the energy-absorbing disc 312 faces the mouth 318 of theinverted funnel-shaped dispenser 310 and defines a distance between thesurface 316 of the energy-absorbing disc 312 and the mouth 318 of theinverted funnel-shaped dispenser 310.

The space 320 between the legs 314 may define a radial flow path acrossthe surface 316 of the energy-absorbing disc 312 for an LCM slurry toexit the LCM placement device 302 onto a test bed with no or negligibledisturbance to the test bed. In some embodiments, the LCM placementdevice 302 may include three legs 314 spaced at 120 degrees around thecircumference of the cylindrical shaft 308 and the perimeter of thesurface 316 of the energy-absorbing disc 312.

In some embodiments, the cylindrical shaft 308, the inverted funnelshaped dispenser 310, the energy-absorbing disc 312, and legs 314 may beformed from a corrosive resistant material, such as certain metals. Forexample, in some embodiments the cylindrical shaft 308, the invertedfunnel shaped dispenser 310, the energy-absorbing disc 312, and legs 314may be formed from stainless steel or aluminum. In such embodiments, asshown in FIG. 3, one end of the legs 314 may be welded to an outer wallof the cylindrical shaft 308 and the other end of the legs 314 may bewelded to the surface 316 of the energy-absorbing disc 312. In someembodiments, the funnel-shaped feeder 304 may be formed from metal orplastic.

FIG. 3 also depicts the general flow of an LCM slurry when using the LCMplacement device 302 to place an LCM slurry on the top of a test bed. Asshown by arrow 322 in FIG. 3, an LCM slurry may first flow in agenerally axial direction when poured into the funnel shaped feeder 304.The energy-absorbing disc 312 may absorb energy from the LCM slurryafter the LCM slurry exits the mouth 318 of the inverted funnel-shapeddispenser 310 and contacts the surface 316 of the energy-absorbing disc312. After the LCM slurry contacts the surface 316 of theenergy-absorbing disc 312, the LCM slurry may flow in a generally radialdirection across the surface 316 of the energy-absorbing disc 312 asgenerally indicated by arrow 324.

FIG. 4 depicts various dimensions of the LCM placement device 302. TheLCM placement device 302 may have a length 400, as defined from the topof the funnel-shaped feeder 304 to the bottom of the energy-absorbingdisc 312. In some embodiments, the height 400 may be about 200 mm. Thefunnel-shaped feeder 304 may have a length 402 and mouth diameter 404.In some embodiments, the length 402 may be about 70 mm and the mouthdiameter 404 may be about 68 mm. The cylindrical shaft 308 may have alength 406, an inner diameter 408, and an outer diameter 410. In someembodiments, the length 406 may be about 100 mm, the inner diameter 408may be about 10 mm, and the outer diameter 410 may be about 15 mm.

As shown in FIG. 4, the inverted funnel-shaped dispenser 310 may have alength 412 and a mouth diameter 414. In some embodiments, the length 412may be about 10 mm and the mouth diameter 414 may be about 15 mm. Thelegs 314 may have a length 416. In some embodiments, the length 416 ofthe legs 314 may be about 15 mm. The energy-absorbing disc 312 may havea length 418 and a diameter 420. In some embodiments, the length 418 maybe about 5 mm and the diameter 420 may be about 68 mm.

FIG. 5 depicts the LCM placement apparatus 302 inserted into a test cell500 in accordance with an embodiment of the disclosure. As shown in FIG.5, the test cell 500 contains a test bed 502 for testing an LCM. The LCMplacement apparatus 302 may be inserted into the test cell 500 via anopening 504 at the top of the test cell 500. For example, the test cell500 may be closed with a lid or other component that is removed forplacement of an LCM slurry via the LCM placement apparatus 302.

The LCM placement apparatus 302 may be inserted into the test cell 500such that the funnel-shaped feeder 304 extends above the opening 504 ofthe test cell 500 and the energy-absorbing disc 312 does not contact thetest bed 502. For example, in some embodiments a space 506 may beprovided between the energy-absorbing disc 312 and the test bed 502 forthe LCM slurry to exit the LCM placement device.

FIG. 6 depicts a process 600 for using the LCM placement device to placean LCM slurry on a test bed in a test cell in accordance with anembodiment of the disclosure. Initially, the LCM placement device may beinserted into a test cell having a test bed (block 602). The LCMplacement device may be inserted such that the funnel-shaped feederextends above the top of the test cell and the energy-absorbing discdoes not contact the test bed and provides sufficient space for an LCMslurry to exit the LCM placement device onto the test bed.

Next, an LCM slurry for testing is poured at an inner wall of the mouthof the funnel-shaped feeder 302 (block 604). In some embodiments, an LCMslurry may be prepared by mixing an LCM with a drilling fluid, such asbentonite mud having water, bentonite, caustic soda, and soda ash. Afterpouring into the LCM placement device, the LCM slurry flows downwardthrough the cylindrical shaft 308 and spreads upon exit from theinverted funnel-shaped dispenser 310 (block 606). The LCM slurry thenimpacts the energy-absorbing disc 312 which dissipates energy andconvers the axial flow from the cylindrical shaft 308 and invertedfunnel-shaped dispenser 310 to radial flow (block 608). The LCM slurrythen settles onto the top of the test bed (block 610). Thus, the deviceand process for placement of an LCM slurry provides a simultaneousreduction of kinetic and potential energies during placement of the LCMslurry on a test bed and changes the flow direction from axial to radialto preserve the quality of the test bed and minimize or prevent anydamage and degradation.

After placement of the LCM slurry, the LCM may be tested for sealing,plugging, and blocking capabilities of the LCM. For example, the testcell may be pressurized and heated to a specific pressure andtemperature, and properties such as fluid loss, spurt loss, total leakoff may be measured via fluid collection from an outlet port at thebottom of the test cell. Additionally, the thickness of a cake formed bythe LCM slurry after pressurization may be measured.

The LCM placement device and process described in the disclosure may beused with different types of test beds, including sand beds, pebblebeds, and carbonate chips beds. The LCM placement device and process maybe used with various test apparatus having a generallycylindrical-shaped test cell. An example test apparatus may have a testcell configured to be pressurized via a gas pressure line connectedthrough a top lid of the test cell and heated via placement in a heatingjacket. In some embodiments, a test cell may have a slotted disc. Insome embodiments, a test cell may have an outlet at the bottom of thetest cell for connection via tubing to a fluid collection device. Insome embodiments, an example test apparatus may be a PermeabilityPlugging Tester (also referred to as “PPT” or “Pore Plugging Test”apparatus) manufactured by OFI Testing Equipment, Inc., of Houston,Tex., USA.

An LCM slurry placement test was conducted using the LCM placementdevice and process with a sand bed as the test bed. FIG. 7 is aphotograph 700 of the sand bed after placement of the LCM slurry usingthe LCM placement device and process described in the disclosure. Asshown in FIG. 7, the top of the test bed shows zero or negligible damageand degradation, thus demonstrating the effectiveness of the LCMplacement device and process in maintaining the quality of a test bed.

Ranges may be expressed in the disclosure as from about one particularvalue, to about another particular value, or both. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value, to the other particular value, or both, along withall combinations within said range.

Further modifications and alternative embodiments of various aspects ofthe disclosure will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the embodiments described inthe disclosure. It is to be understood that the forms shown anddescribed in the disclosure are to be taken as examples of embodiments.Elements and materials may be substituted for those illustrated anddescribed in the disclosure, parts and processes may be reversed oromitted, and certain features may be utilized independently, all aswould be apparent to one skilled in the art after having the benefit ofthis description. Changes may be made in the elements described in thedisclosure without departing from the spirit and scope of the disclosureas described in the following claims. Headings used in the disclosureare for organizational purposes only and are not meant to be used tolimit the scope of the description.

What is claimed is:
 1. A method of manufacturing an apparatus forplacement of a lost circulation material (LCM) on a test bed in a testcell, the method comprising: connecting a funnel-shaped portion to afirst end of a cylindrical shaft, the funnel-shaped portion comprising amouth having a first diameter and an outlet having a second diameter,the first diameter greater than the second diameter; connecting aninverted funnel-shaped portion to a second end of the cylindrical shaft,the inverted funnel-shaped dispenser comprising an inlet having a thirddiameter and a mouth having a fourth diameter; and coupling a solid discto the inverted-funnel shaped portion via a plurality of legs, such thata surface of the solid disc faces the mouth of the invertedfunnel-shaped dispenser to define a distance between the surface of thesolid disc and the mouth of the inverted funnel-shaped dispenser,wherein apparatus is configured to convert axial flow through thecylindrical shaft to radial flow across the surface of the solid disc.2. The method of claim 1, wherein the step of coupling a solid disc tothe inverted-funnel shaped portion via a plurality of legs compriseswelding the legs to the inverted-funnel shaped portion.
 3. The method ofclaim 1, wherein the solid disc is formed from stainless steel.
 4. Themethod of claim 1, wherein the plurality of legs comprises three legsaround the circumference of the cylindrical shaft such that each leg islocated 120 degrees from an adjacent leg.